Fluid pressure brake system



Jan. 23, 1940. Q J ANZ 2,187,789

FLUID PRESSURE BRAKE SYSTEM lFiled March 26, 1938 i@ ATTORNEY PatentedJan. 23, 1940 UNiTED- STATES PATENT. OFFICE Applicatie?1 biaclf, (2158;asse-T630. 198,291

' My invention relates to fluid pressure brake systems, and particularlyto uid pressure brake systems of the type commonly employed onautomotive vehicles.

One object of my invention is to provide a simple, reliableand"eflective means whereby the operator of a vehicle may, when desired,maintain the brakes in their applied positions following a brakeapplication without the necessity for l0 maintaining hisfoot on thebrake pedal.

Another object of my invention is to provide an electrically controlledvalve mechanism which can bevinserted in a brake system of the typedescribed at any suitable location between the 1I source of fluidpressure and one or more of the wheel cylinders, and which is effectivewhen operated to retain the iiuid in such cylinder or cylinders at anypressure to which it has beenl raised by an application of the brakes.

A further object of my invention is to provide switch means which can besecured to the gear shift lever of an automotive vehicle in place of theusual knob, and which is so constructed that it can be readily operated,to effect the control of the above mentioned valve mechanism, by thesame hand with which the operator shifts gears without removing his handfrom the gear shift lever or interfering with the' shifting of thegears. g'

lurther objects and characteristic features of my invention will appearas the vdescription proceeds.

I shall describe one form of iiuid pressure brake system embodying myinvention, and shall then point out the novel features thereof inclaims.

In the) accompanying drawing, Fig. 1 is a schematic view illustratingone form of. brake system embodying my invention. Fig. 2 is an enlargedsectional view of the brake unit l indicated diagrammatically in Fig. 1.Fig. 3 is an enlarged vertical sectional view of the combined reservoirand master cylinder unit A shown in Fig. l. Fig. 4 is an enlargedvertical sectional view of the magnet valve B shown in Fig. 1.

Fig. 5 is an enlarged vertical sectional view of the switch C shown inFig. 1. Fig. 6is a sectional view taken on the line VI-VI of Flg.l5.

Similar reference characters refer to similar parts in each of theseveral views.

A brake system embodying my invention comprises, in general, anysuitable ymeans for supplying iiuid pressure to one or more fluidpressure operated brake units, a magnet valve effective when energizedfor maintaining the fluid in such brake unit or units, as the case maybe, following an application of the brakes to maintain the brakes intheir applied positions, and switch means for controlling theenergization of the magnet valve. In the particular embodiment of myinvention illustrated in the drawing, the li5 brake system is of thehydraulic type commonly employed on automobiles, and includes four brakeunits I, 2, 3 and 4,' one of which will usually be located at each'wheel of the automobile, although it is obvious that these units may beasso- 10 ciated with the propeller shaft, or may be placed at any othersuitable location or locations. 'I'he units I, 2, 3 and I may have anyusual construction, and as here shown, are each similar to the l unit Iillustrated in detail in Fig. 2. Referring 15 to Fig. 2, this unitcomprises a wheel cylinder 5 mounted on a backing plate 6 attached tothe axle or differential housing 1. The cylinder 5 includes opposedpistons 8, each of which is connected by a link 9 with a brake shoe I0pivoted 20 at II to the backing plate 6. Guide means I3 are provided forthe brake shoes as are also the retracting springs I5 which lnormallyhold the brake shoes I0 against suitable stops I6. Associated with thepistons 8 are exible rubber g5 cups I1 which are held against the facesof the pistons by an interposed spring I 8. The inner ends of the links9 rest in sockets in the rear sides of the pistons 8, and when the stopsI6 are ad- K justed to position the shoes closer to the drimi I9 an'fthe wheel cylinder. through a pipe or conduit 22,v

and in order to prevent breakage of this conduit due to the necessarymovement of the wheels relative to the vehicle frame, the conduit isprovided adjacent the point where it is connected to 45 the wheelcylinder with a flexible portion 23. It will be apparent that when fluidis supplied to the wheel cylinder 5, the pistons 8 will move outwardlyin the cylinder and will act through the associated links 9 to rotatethe brake shoes I0 50 about their pivots I I to the positions in whichthey frictionally engage the brake drum, thereby effecting anapplication of the brake.

The means shown in the drawing for supplylng iiuid to the wheelcylinders to effect an ap- 55 plication of the brakes comprises acombined reservoir and master cylinder unit A (see Fig. 3) consisting ofa suitable casing containing a reservoir and a master cylinder 26. Thevmaster cylinder 26 has a piston l2 reciprocally mounted therein. Thepiston comprises a face portion 21 adapted to carry a packing cup 28,and a rearwardly extending flange 29 spaced from the cylinder wall. Theend of the rearwardly extending flange 29 has a radial flange 30 whichcontacts with the cylinder wall to guide the piston in the cylinder,forming an annular recess 3| around the piston. A ring 32 is retained inthe end oi the cylinder by a split ring33, and is adapted to limit themovement of the piston toward the rear end of the cylinder. is alsoprovided with a socket 34 which engages the rounded inner end of a pushrod 35 by means of which the piston may be moved. The push rod extendsoutside of the cylinder through a flexible boot 36, and is adjustablyconnected at its outer end with a suitable operating lever which is hereshown as the usual foot pedal 31, but which may, if desired, be operatedby hand or by suitable power means. A compressed coil spring 38 isinterposed between the packing cup 28 and the outlet end of the mastercylinder and serves to return the piston to the retracted position shownwhen the foot pedal is free to move to its released position. The mastercylinder 26 is adapted to communicate with the reservoir 25 through therestricted port 39 when the cylinder occupies its retracted position.The discharge end of the cylinder is connected with the conduit 22leading to the wheel cylinder as will readily be seen from an inspectionof Fig. 1.

The magnet valve is designated as a whole by the reference character Band in the preferred form illustrated in Fig. 4, is of the solenoidactuated rubber diaphragm type. Referring to Fig. 4, this valve as hereshown comprises a shell made up of a metal tube 40 oi.' suitablemagnetizable material, preferably wrought iron, internally threaded atits opposite ends to receive two magnetizable end members 4| and 42which are also preferably of wroughtiron. and which are screwed into thetube to the positions in which flanges 43 formed on these members engagethe ends of the tube. The lower end member 42 is provided with an axialhole 42a, the upper end of which is surrounded by an annular boss 44,and the lower end of which communicates with an annular recess 45. Theupper end member 4| is likewise provided with an axial hole 41a which issomewhat larger in diameter than the hole 42a, and extending into theshell through the hole 41a is a bushing 46 of suitable nonmagneticmaterial such as brass, the lower end of which engages the boss 44. Aplunger 41 of suitable magnetizable material'such as wrought iron isslidably mounted in the bushing 46, and is secured to a valve stem 48which extends downwardly through a hole 49 formed in the plunger, andthrough the hole 42a in' the end member 42, and is provided at its lowerend with an enlarged head 50 which fits into the recess 45 with someclearance. For reasons which will appear hereinafter it is desirable tobe able'to adjust the stroke of the plunger, and to this end the upperend of the valve stem is screw-threaded, and the upper end of the hole49 in the plunger is tapped in the manner shown. Furthermore, the upperend of the valve stem is providedwith a saw kerf 5I for the reception ofa screw driver or like tool to enable the valve stem t0 be readilyrotated The pistonv relative to the plunger, and with a jam nut 52 tolock the valve stem in its adjusted position. Surrounding the bushing 46is a winding 53 wound on an insulating spool 54, the upper head of whichis provided at its opposite sides with threaded metal inserts 55 whichare connected with the opposite ends of the Winding. The inserts 55align with holes 56 formed in the tube 40 through which terminal posts51, which are screwed at their inner ends into the inserts, extend. Theterminal posts are suitably insulated from the tube, and are providedwith nuts 51a for securing circuit wires to the terminal posts.

The valve'portion of the magnet valve comprises a casing 58 preferablyof brass or bronze provided at its upper end with an annular iiange 59which is securely clamped against the lower end member 42 by means oi'screws 6U distributed at spaced points around the flange. A flexiblediaphragm 6|, preferably rubber, is. interposed between the flange andthe end member 42, and this diaphragm cooperates with the enlarged head50 of the valve stem 48 and with an annular valve seat 62 formed in thecasing directly below the head 50, in such manner that when the winding53 is deenergized fluid is free to flow from a threaded opening 63formed in one side of the casing through a passageway 64 and chamber 64awhich surrounds the valve seat, into a threaded opening 55 formed in theother side of the casing directly opposite the opening 63, or viceversa, but that, when the winding 53 is energized the diaphragm 6l willbe pressed into engagement with the valve seat 62 by the head 50 of thevalve stem, and will cut oil communication between the openings 63 and65 through the passageway 64 and chamber 64a. The valve portion of themagnet valve also includes a spring pressed check valve 66 which permitsfluid to flow from the opening 63 to the opening 65 through passageways61, 61a and 68 but which eectively prevents the iiow of fluid, from theopening to the `opening 63 through these last mentioned passageways. Itwill be seen, therefore, that when the magnet valve is energized, fluidcan always flow through the valve from the opening 63 to the opening 65,but is effectively prevented from flowing in the opposite direction.

The magnet valve B may be inserted into the brake system at any desiredlocation between the master cylinder and as many of the brake units asit is desired to retain in their braking positions by the magnet valvefollowing a brake application. As shown in the drawing, the valve isinserted into the conduit 22 adjacent the master cylinder 26 in suchmanner that ii the magnet valve is energized when the brakes areapplied, the valve will trap fluid in the wheel cylinders 5 oi all fourbrake units, and it will be apparent, therefore, that by energizing themagnet valve prior to making a brake application, or while the brakesare in their applied positions, all four brake units may be maintainedin their braking positions as long as the magnet valve subsequentlyremains energized, even though the operator removes his foot from thefoot pedal 31.

When the magnet valve is disposed in the position shown it mayconveniently be secured to the brake cylinder casing by a suitable strap40a which fits into an annular groove 40h formed in the outer face ofthe tube 40, and which is bolted at its ends to the brake cylindercasing.

'I'he switch means C for controlling the energization of the magnetvalve is preferably so constructed that it can be secured to the gear laleman ible contact ilnger 16 to form a contact 16-16.

The member 15 is threaded to receive a screw 11 which passes upwardlythrough ahole 18 in the base portion 1li, whereby the member 15 may beelectrically connected with the gear shiftlever, and hence with theframe of the vehicle lasA indicated by the wire 19 and conventionalground symbol 80. The ilexible contact iinger 16 is secured at one endto the head by means oi a screw 16a which passes through the nger, andis screwed into a threaded insert 8|* moulded into the head. 'Ihe screw16a also serves to secure a conductor 82 to the linger, which conductor,in turn, is connected to the one terminal post 61 oi.' the magnet valveBin the manner shown in Figs. 1 and 5. The other terminal post 51 isconnected by means of a conductor 83 to one terminal of the usual carbattery D, the other terminal of which is grounded to the car frame, asindicated by the conventional ground symbol 84. In actual practice, thelast mentioned terminal 51 will usually be connected with the battery Dthrough the ignition switch in such manner that the terminal will onlybe connected to the battery when the ignition switch is. on. It will beseen,

therefore, that when the contact 15-16 is closed the magnet valve willbecome energized. The contact 15-16 is arranged to be closed by `anoperating member 85 of suitable moulded insulating material. The member85A projects out through a slot 86 formed in the top oi the head 12, andis provided at its lower 4end with a cross pin 81 which is slidably androtatably mounted 'in vertical yguide slots 88 formed in the head 12`member in the position shown and in which the contact 15-16 is open, butthat, the contact can be closed either by depressing the operatingmember, or by rotating it downwardly through a slight angle, inwhichlatter case the cam surface 90 will cooperate with the nger 16 in suchmanner that the contact will remain closed even though the operatorreleases the operating member. After the contact has been closed byrotating the operating member downwardly, it can be subsequently openedby restoring the operating member to the position shown.

With the brake system constructed in the manner described it will beobvious that when the member 86 to close the contact 18-18 either betorehe has applied the brakes, or while they are still in their appliedpositions. The'closing o! the contact 16-18 will, as was previouslypointed out, cause the magnet valve B to become energized and trap thefluid in the wheel cylinders 6 at the highest pressure to which it israised while the magnet valve is energized, thus permitting the operatorto remove his foot from the foot pedal,

- and hence permitting him to obtain better control oi his car. If theoperator only wishes to maintain the brakes in their braking positionmomentarily he will usually operate the contact by depressing theoperating member 86 with the thumb or other part oi the hand with whichhe operates the gear shift lever, but if he wishes to maintain thebrakes in their applied position e for any appreciable period of time,or without the necessity for maintaining his hand on the v gear shiftlever, he'will usually operate the contact by rotating the operatingmember to its lowermcst position to thus lock the contact 16--18 in itsclosed position. When he desires to subsequently releasethe brakes hewill restore the member 85, or permit it to move due to the bias of thefinger 16, to the position shown.

It should be pointed out that due to the fact that the area around thevalve seat 62 is larger than the area within the valve seat 62 thepressure tending to unseat the diaphragm 6I due to uid owing toward thewheel cylinders is greater. than that tending to unseat the valve due toiluid owing in the opposite direction, and that.' as a result, byproperly proportioning the parts, the valve may be so constructed thatit will permit fluid to ilow to the wheel cylinders even though themagnet valve is energized, but will not permit it to ilow in theopposite direction when the magnet valve is energized, without thenecessity for the check valve 66. This latter construction increases thesimplicity of the system and tends to decrease its cost, as well as toeliminate a possible source of iiuid leakage.

I have found that with a brake system embodying my invention a magnetvalve of relatively small size requiring an energizing current of notmore than 5 amperes at thev battery voltage usually provided onautomobiles can be successfully used to maintain the pressure in theWheel cylinders at a sufliciently high value to hold an automobile forlong periods of time on the steepest grades on which it would ever beused.

One advantage of a brake system embodying -my invention isY that it canbe applied to any form of automobile which is provided with iluidpressure brakes regardless of whether the brakes are of the hydraulic,air pressure, or vacuuml type.

Another advantage of a brake system embodying m'y invention is thatthere is a minimumnumber of parts to wear, which materially adds to thereliability and practicability of the system.

A further advantage of a system embodyingmy invention is that it isuniversal in its application toautomobiles having iluid pressure brakes,and readily lends itself to use on such vehicles.

Although I have herein shown and described only one form ofl brakesystem embodying my ,claim is:

1. In a hydraulic brake system for automobiles, the combination with awheel cylinder and a master cylinder connected by a iluid conduit, avalve in said conduit for controlling the now of duid through saidconduit comprising a valve seat and a rubber diaphragm cooperating withsaid seat, and a solenoid operated valve stem cooperating with saiddiaphragm to force said diaphragm into engagement with said seat toclose said valve.

2. In a hydraulic brake system for automobiles, the combination with afluid pressure responsive brake unit and means connected with said unitfor supplying fluid pressure to said unit, of a valve interposed betweensaid unit and said means, said valve comprising an annular valve seat, arubber diaphragm disposed above said seat, and a solenoid actuated valvestem disposed above said diaphragm and effective when said solenoid isoperated to force said diaphragm into engagement with said seat, theparts being so arranged and so proportioned that when said diaphragm isengaging said seatl a larger area of said diaphragm will be subjected tothe pressure of the iluid tending to ilow toward said unit than issubjected to the pressure of the iluid tending to flow in the oppositedirection, whereby it said solenoid is energized when said means isoperated said valve will be forced open to permit the iiuid'to flow tosaid unit but will be effective to prevent iiuid from escaping from saidunit as long as said solenoid remains energized.

3. In a uid operated brake system for vehicles, the combination with afluid responsive brake applying means and a conduit through which iiuidis at times supplied to said means to cause a brake application, of avalve in said conduit comprising a valve seat, a exible member effectivewhen pressed against-said seat to prevent the iiow of uid through saidconduit in the direction to release said brake applying means, and amagnet- A ically operated valve stem cooperating with said member topress said member-against said seat.

4. In a fluid operated brake system for vehicles, the combination with aiuid responsive brake applying means and a conduit through which fluidis at times supplied to said means to cause a brake application, of avalve in said conduit for controlling the iiow of iiuid through saidconduit, said valve comprising a valve seat, a diaphragm disposed abovesaid seat, and a magnetically operated valve stem disposed abovesaid,diaphragm and effective when operated to force said diaphragm intoengagement with said seat, said diaphragm being of a material which issuiliciently yieldable to permit the necessary movement thereof and toprovide a good seal when pressed against said seat.

5. In a iluid operated brake system for vehicles, the combination with ailuid responsive brake applying means and a conduit through which fluidis at times supplied to said means to cause a brake application, of avalve in said conduit for controlling the flow of fluid through saidconduit, said valve comprising a valve seat, a diaphragm disposed abovesaid seat, a magnetically operated valve stem disposed above saiddiaphragm and eiective when operated to force said diaphragm intoengagement with said seat, said diaphragm being of a material which issuiiiciently yieldable to permit the necessary movement thereof and toprovide a good seal when pressed against said seat, and means forvarying the stroke of said valve stem to enable the pressure with whichaleman said valve stem forces said diaphragm into engagement with saidseat to be varied.

6.' In a uid operated brake system for vehicles, the combination with ailuid responsive brake unit and means connected with said unit i'orsupplying fluid to said unit, of a valve interposed between said unitand said means, said valve comprising a valve seat, a diaphragmcooperating therewith, and a solenoid operated valve stem eilective whensaid solenoid is energized to torce said diaphragm into engagement withsaid seat, said diaphragm being oi' a material which is sufiicientlyyieldable to provide a good seal when pressed against said seat, and theparts being so proportioned that when said solenoid is. energized alarger area of said diaphragmfwill be subjected to the pressure of thefluid flowing in a direction to operate said unit than is subjected tothe pressure of the fluid iiowing in the opposite direction, whereby ifsaid solenoid is energized when said means is operated said valve willopen to permit operation of the unit but will be eective to retain theunit in its operated condition as long as said solenoid remainsenergized.

7. In a uid operated brake system for vehicles, the combination with ailuid pressure responsive -brake unit and means connected with said unitfor supplying fluid pressure thereto, of a valve interposed between saidunit and said means, said valve comprising a magnetizable shell, twomagnetizable end members secured to the opposite ends of said shell, avalve stem slidably mounted in an axial hole in one of said end membersand having an enlarged head disposed in a recess surrounding the outerend of said hole, a magnetizable plunger slidably mounted in an axialhole in the other end member and provided with an axial hole whichreceives said valve stem,

. means for adjustably securing said valve stem to said plunger, awinding in said shell surrounding said plunger, a valve casing securedto said one end member and provided with an annular valve seat directlyopposite said enlarged head of said valve stem, and a rubber diaphragmclamped between said valve casing and said one end member andcooperating with said valve stem to close said valve when said windingis energized, said diaphragm also serving as a means to prevent theescape oi' iluid from said valve casing at its region of attachment tosaid one end member.

8. In a fluid operated brake system for vehicles, the combination with ailuid pressure responsive brake unit and means connected with said unitfor supplying fluid pressure thereto, of a valve interposed between saidunit and said means for controlling the ow 'of fluid away from saidunit, said valve comprising a' solenoid provided with a plungeractuating a-valve stem, a casing secured to one end of said solenoid andprovided with an annular valve seat in alignment with said valve stem,and a diaphragm clamped between said casing and said solenoid andarranged to be moved into engagement with said seat by said stem toclose said valve when said solenoid is energized, said diaphragm beingof a material which is sufiiciently yieldable to permit the necessarymovement thereof and to provide an eilicient seal when pressed againstsaid seat.

9. In a fluid operated brake system for vehicles, the combination with afluid pressure responsive brake unit and means .connected with said unitfor supplying uid pressure thereto, of a valve interposed between saidunit and said means for controlling the flow of uid away from said unit,

said valve comprising a' solenoid provided with a plunger actuating avalve stem, a casing secured to one end of said solenoid and providedwith an annular valve seat in alignment with said valve stem, adiaphragm clamped between said casing and said solenoid and arranged tobe moved into engagement with said seat by said stem to close said valvewhen said solenoid is energized, said diaphragm being of a materialwhich is suil'lciently yieldable to permit the necessary movementthereof and to provide an eicient seal when pressed against said seat,and means for adjusting the position of said valve stem relative to saidplunger to enable the pressure with which said stem forces saiddiaphragm into engagement with said seat to be varied.

10. In a fluid operated brake system for vehicles, the combination witha -fluid pressure responsive brake unit and means associated with saidunit for supplying iluid pressure thereto, of a valve interposed betweensaid unit and said means for controlling the flow of fluid away fromsaid unit, said valve comprising a solenoid provided with a plungeractuating avalve stem, a casing secured to one end of said solenoid andprovided with an annular valve seat in alignment with said valve stem,and a diaphragm clamped between said casing and said solenoid andarranged to be moved into engagement with said seat by said stem toclose said valve when said solenoid is energized, said diaphragm beingof a material which is sulciently yieldable to permit thenecessarymovement thereof to enablesaid valve to be effectively closedand to insure an eiicient seal between said casing and said solenoid.

- 11. In a fluid operated brake system for vhi-` cles, the 'combinationwith a fluid responsive brake applying means and a conduit through whichuid is at times supplied to said means to cause a brake application, ofa valve in said conduit for controlling the ow of fluid through saidconduit, said valve comprising two relatively movable valve parts one ofwhich is sufiiciently flexible when held in engagement with the otherpart to provide a seal which is effective to prevent the flow of uidthrough said conduit in the direction to release the brakes, andsolenoid operated means for at times holding said valve parts inengagement with each other to prevent the release of the brakesfollowing a brake application.

GEORGE J. LANZ.

